Inheritance and Isozyme Diversity for GPI and PGM among Grape Cultivars

Leaf isozymes of 145 cultivars of grapes ( Vitis vinifera L. and Vitis spp. ) were separated via starch gel electrophoresis. They could be separated into 52 groups using glucosephosphate isomerase (GPI) and phosphoglucomutase (PGM) isozymes. Twenty-four cultivars had unique combinations of isozyme patterns. Two loci, Gpi-2 and Pgm-2, were identified and shown to be simply inherited with multiple alleles at each locus. The mean heterozygosity for the two loci (Gpi-2 and Pgm-2) among all the cultivars was 57.5%, indicating a high level of genetic variability among these cultivars. Indirect evidence for expressed linked lethal alleles was demonstrated by the missing classes in Gpi-2 and Pgm-2 segregation ratios (1:2:0 ratios) in several selfed progeny families. Chemical name used: methyl[1-(methylethyl)-1 H -benzimidazol-2-y]-carbamate (benomyl).